Liquid fuel heater improvement

ABSTRACT

An improvement in a liquid fuel heater causing ignition prior to total vaporization of the fuel. Asbestos wick material is positioned within a cavity in a porous ceramic block adjacent to a liquid fuel supply such that the wick becomes saturated with fuel. An electrical resistance igniter extends partially into the cavity and causes the fuel to ignite more efficiently then ordinarily possible due to vaporization of the fuel within the ceramic block.

United States Patent 1 Stanley et a1.

[ LIQUID FUEL HEATER IMPROVEMENT [75] Inventors: Edward I. Stanley, North Olmsted;

Donald G. Batchelor, Chagrin Falls, both of Ohio [73] Assignee: Stacee Manufacturing, Inc.,

Cleveland, Ohio 22 Filed: Mar. 4, 1974 21 App1.No.:447,671

[52] US. Cl 431/7, 431/170, 431/262 [51] Int. Cl. F23d 3/40 [58] Field of Search 431/170, 262, 7, 326, 328,

[56} References Cited UNITED STATES PATENTS 2,710,652 6/1955 Ambrose 431/262 X [451 Nov. 19, 1974 Raymond et a1 431/262 Carlsson l. 431/170 Primary Examiner-Edward G. Favors Attorney, Agent, or FirmCain and Lobo [57] ABSTRACT An improvement in a liquid fuel heater causing ignition prior to total vaporization of the fuel. Asbestos wick material is positioned within a cavity in a porous ceramic block adjacent to a liquid fuel supply such that the wick becomes saturated with fuel. An electrical resistance igniter extends partially into the cavity and causes the fuel to ignite more efficiently then ordinarily possible due to vaporization of the fuel within the ceramic block.

8 Claims, 4 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to liquid fuel heaters and, more particularly, to an improved electrical resistance heating element and ceramic block causing the ignition of liquid fuel.

2. Description of the Prior Art Prior art liquid fuel heaters often encountered difficulties when an attempt was made to operate the heaters at very low temperatures, particularly with lower grade fuels. The orientation of the heater, other than a predetermined position, also presented serious problems with respect to starting and running the heater. An improvement on the prior art devices is disclosed in U.S. Reissue Pat. No. Re 25,970, issued on Mar. 1, 1966 to Richard J. Brown and entitled LIQUID FUEL HEATER.

The above noted reissue patent discloses the use of a porous ceramic block for vaporizing the fuel. This use of ceramic material to assist in vaporization is not new in the art as shown by U.S. Pat. No. 2,199,777, issued on May 7, 1940 to Kemper P. Brace and entitled LlQ- UID FUEL BURNER. This patent discloses a ceramic element having horizontal apertures extending therethrough. In such a case, the liquid fuel is dispersed into the horizontal apertures through which an air current is caused to flow. The air passing by the fuel results in the fuel being vaporized and thus more easily ignited.

The direction in which the apertures are constructed is extremely important as to the correct operation of the heater. Thus,.if the apertures vary to any considerable degree from horizontal, the liquid fuel is capable of flowing through the ceramic material at a rate of speed rendering vaporization impossible. Such a result of course rules our orientational changes of a heater so constructed.

The above noted reissue U.S. Pat. No. Re 25,970, remedies the problem of orientational changes with regard to liquid fuel heaters by using a ceramic block material without apertures for the fuel flow. The fuel travels through the intersticial pores present in the ceramic material by capillary action. Air is forced over the surfaces of the ceramic block to cause vaporization of the liquid fuel. An electrical resistance heating element is positioned within the ceramic block with the intended purpose of heating the entire ceramic block and therefore the vaporized fuel to an appropriate temperature resulting in ignition of the fuel.

Since the ceramic block has effectively no apertures through which the liquid fuel is able to readily move, the heater is capable of operation in any possible orientation. However, since the electrical heating element must raise the temperature of the entire ceramic block, or at least a considerable portion thereof, to a temperature sufficient for the combustion of the fuel to be sustained, ignition of the heater requires a relatively large amount of time. Even after the required length of time, combustion may not occur effectively, dueto too much fuel being present at one time.

In an effort to speed up ignition of the liquid fuel, prior art devices have attempted to use a wick material, such as for example asbestos cloth, to vaporize the fuel more quickly and thus speed up ignition. Such a use is illustrated by U.S. Pat. No. 2,286,854, issued on June 2 I6, 1942 to Harry B. Holthouse and entitled HEATER.

Problems were encountered with solutions involving wick materials in that the fibrous wick readily became contaminated with deposits of carbon and dirt particles from the fuel. lnefficient operation quickly resulted from the contamination of the Wick material.

SUMMARY OF THE INVENTION The primary object of this invention is to provide a new and improved liquid fuel heater which results in ignition of the fuel regardless of the relative orientation of the heater.

Other objects of this invention are to provide a new and improved liquid fuel heater which vaporizes the fuel through the use of a refractory ceramic block; and, which disperses the liquid fuel into the ceramic block to be vaporized within a wick material and the ceramic block.

and improved liquid fuel heater which is able to ignite the fuel at an accelerated rate of speed in comparison to prior art devices; which utilizes the initial ignition of the fuel to heat the ceramic block; and, which utilizes a wick material to effect accelerated ignition and combustion without resulting in adverse effects due to contamination of the wick material from impurities of the fuel.

The invention has as additional objects the providing of a new and improved liquid fuel heater which results in the ignition of fuel dispersed into the wick material; which assists in vaporizing the fuel in the ceramic block by heating the block; and, which results in the effective ignition of all the fuel in the intersticial pores of the ceramic' block.

Still further objects of the invention are to provide a new and improved liquid fuel heater including an electrical resistance ignition coil which is inserted only partially into the ceramic block; which is positioned adjacent to the wick material; and, which results in the ignition coil flashing and tiring the fuel retained by the wick material.

Yet another object of this invention is to provide a new and improved liquid fuel heater which ignites and operates effectively as a result of current provided by a direct current power source.

Still a further object of this invention is to provide a new and improved liquid fuel heater which is capable of igniting and sustaining combustion of heavier grades of liquid fuels ordinarily resulting in contamination of the igniterand ceramic block due to carboning causing inefficient combustion as a result of an excessively rich fuel to air mixture.

A further object of the invention isthe provision of a new and improved liquid fuel heater which ignites the fuel quickly and thus results in the assured production of heat at full capacity without flooding due to excessive fuel in the burner of the heater.

A still further object of this invention is to provide a new and improved liquid fuel heater which obtains one or more of the objects and advantages set forth above.

These and other objects and advantages ofthis invention will become apparent from the following description thereof, in view of the accompanying drawings.

Further objects of this invention are to provide a new- I BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, at a reduced scale, of the heater of the present invention.

FIG. 2 is a cross-sectional view of the heater of this invention taken substantially along line 2-2 of FIG. 1.

FIG. 3 is a longitudinal cross sectional view of the heater of the present invention.

FIG. 4 is a perspective view showing the arrangement of the ceramic block, the wick material and the igniter.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a liquid fuel heater, indicated generally at 10, including the improvement of the present invention. The heater may be mounted at any orientation through the use of mounting brackets 12. A pressurized fuel supply, e.g., fuel storage tank and pressure pump, is connected at an appropriate input 13. Likewise, appropriate electrical connections are made through a connector 15. Such electrical connections include a source of power, e.g., l2 or 24 volts DC, a temperature controlled thermostat and possibly a remote control unit. A cover 17 is provided to conceal and protect the electrical and fuel components on the heater 10. The cover 17 is secured to the heater 10 by means of any suitable fastening devices such as indicated at 18.

The operation of the heater 10 is basically identical to a number of the prior art devices. An end cap 20 provides the intake for fresh air to operate the heater 10. The end cap 20 may include louvers, a screen or may be entirely open. A fan (not shown in FIG. 1)

' draws fresh air both past and through a combustion area, generally indicated at 21, thereby causing combustion of the fuel and heating of air passing.

FIG. 2 more clearly illustrates a burner 24, located generally in the area indicated at 22, which performs the function of mixing of the liquid fuel and the air drawn into the combustion area 21. A ceramic block 26 constructed of a porous refactory, ceramic material is positioned in the center of the burner 24 which is cylindrical in shape. The ceramic block 26 is attached to one end of the burner 24 by any suitable fastening device such as a screw 27. The open face of the ceramic block 26 is covered by a metal plate 28 which is also held in place by the screw 27. The metal plate 28 assures that burning of the liquid fuel occurs at the edge of the ceramic block 26 and not at the open face.

An electrical igniter 30 and a fuel feed tube 32 enter the burner 24 through the burner area 22 by reason of correspondingly mating connections 33 and 34, respectively. The electrical igniter 30 and fuel feed tube 32 in turn enter the ceramic block 26 into appropriate apertures 37 and 38, respectively, provided in the block 26. The apertures 37 and 38 are connected internally with respect to the ceramic block 26 by reason of a cavity 40. The particular arrangements of the ceramic block 26 are more readily apparent with regard to FIG. 4.

Asbestos wick material in the form ofa rope wick 42 v is shown in FIG. 4, removed from the cavity 40 where normally positioned (as shown in FIG. 2 and by phantom lines in FIG. 4). With the rope wick 42 positioned in the cavity 40 the electrical igniter 30 and the fuel feed tube 32 are directly adjacent to the rope wick 42 when the burner 24 is assembled. When liquid fuel is permitted to flow through the fuel feed tube 32 the rope wick 42 becomes completely saturated with fuel almost immediately. The ceramic block 26 likewise begins to become saturated by taking on liquid fuel in the pores of the refactory material. When the electrical igniter 30 is connected to power through an appropriate electrical circuit, the liquid fuel which has saturated the rope wick 42 quickly ignites.

Ignition and the resultant combustion of the liquid fuel may be more fully described with the air of FIG. 3. As mentioned above, behind the end cap 20 is a fan 46 which draws fresh air into the heater 10 for purposes of combustion and heating. The fan 46 is driven by a motor 48 contained internally with respect to the heater l0 and powered by the DC. supply through connections with appropriate circuitry. The motor 48 has another fan 50 driven by the opposite end of the same shaft. The motor 48 is mounted to a burner casing 52 with the fan 50 being positioned within the casing 52. The burner 24 is positioned within the burner casing 52 and directly ahead of the fan 50. The burner casing 52 is designed to allow fresh air, drawn by the fan 46, to be further drawn into the casing and through the fan 50.

Details of the burner 24 and ceramic block 26 construction and function may be obtained by reference to the above mentioned reissue US. Pat. Re 25,970. Briefly, the burner 24 has a first and second set of apertures extending around the entire circumference of the burner, indicated generally at 54 and 55 respectively. The first set of apertures 54 is positioned oppposite the edge of the ceramic block 26 and is intended to assist in the ignition of the fuel. The second set of apertures 55 is beyond the open face of the ceramic block 26 and is intended to sustain combustion of the fuel after ignition. The fan 50 forces air into the first 54 and second 55 apertures and results in the desired ignition and combustion of the liquid fuel.

The advantages of the invention are embodied in the ignition of the fuel. In this regard, when operation of sults in the saturation of the porous refactory ceramic block 26.

Also, upon initiation of the operation of the heater 10 the electrical igniter 30 is energized. The electrical igniter 30 comprises a high resistance glow plug which results in a temperature of about 2,000 F. being produced by coils at the end of the igniter 30. As evident from both FIGS. 2 and 3, the electrical igniter 30 is positioned directly adjacent to the rope wick 42. Further, the igniter 30 is only partially inserted into the aperture 37 in the ceramic block 26. This arrangement is due to the igniter 30 not being primarily responsible for heating the entire ceramic block 26.

The igniter 30 causes the fuel present in the rope wick 42 to result in a flame within about 15 seconds of the commencement of operation. This time is, of course, dependent upon environmental conditions such as temperature, wind, humidity and a number of other variables. By comparison, the igniter of prior art devices such as disclosed in the above noted reissue U.S.

Pat. -Re 25,970, required about 2 minutes of energization before any flame occurred assuming identical environmental conditions.

In the case of the present invention, the flame produced by the igniter 30 results in the entire ceramic block 26 being heated. Meanwhile, air is forced by the fan 50 through the first set of apertures 54 to cause vaporization of the fuel in theblock 26. As the vaporization of the fuel proceeds and the ceramic block 26 continually experiences an increase in temperature, the flame produced by the igniter 30 increases in intensity. As described above, the surface of the ceramic block 26 facing the combustion chamber 57 is covered by the metal plate 28. As further noted above, this metal plate 28 assures that the combustion does not occur at the surface of the block 26 but only at the edge of the block.

As combustion proceeds, the flame produced by the igniter 30 expands around the circumference of the ceramic block 26 until the entire periphery supports the flame. At this time air forced through the second set of apertures 55 by the fan 50 mixes with the burning vaporized fuel and results in increased combustion. When the flame has reached a predetermined distance from the ceramic block 26, indicated generally by arrows at A, appropriate electrical circuitry disconnects the power from the electrical igniter 30. From this point on, the combustion if self-sustaining and dependent only upon the delivery of fuel to the ceramic block 26 and the continued operation of the motor 48.

When the heater is operating at full combustion, sufficient amounts of liquid fuel are provided to the burner 34 by reason of a metering valve (not shown in the figures) to enable the flame to exist at a predetermined point within the combustion chamber 57, indicated generally at B. Various methods of sensing may be employed to assure that combustion remains as desired once fully established. By controlling the amount of fuel delivered to the burner 24, under the direction of the sensed variable, combustion may be maintained at any level.

Theexhaust from the combustion occurring within the combustion chamber 57 exists, due to pressure differences, through an exhaust port 59. Finally, the fresh air entering through the end cap into the fan 46 rushes past the combustion chamber 57 causing the air to become heated. This heated air exits the heater 10 as shown by the arrows indicated generally at C. The heated air may be directed in any fashion desired by means of baffles, duct work and registers.

When the heater 10 is desired to be shut off, the fuel supply need only be terminated by appropriately disengaging the above mentioned metering valve. As the fuel remaining in the ceramic block 26 burns, the flame diminishes until combustion ceases to exist. At this time, appropriate electrical circuitry de-energizes the motor 48. This continued operation, purging of the heater 10, is desirable in order that all remaining fuel be consumed. In the absence of such a requirement, any fuel remaining in the ceramic block 26 may cause contamination of the refactory material with a resultant detrimental effect as to further operations of the heater 10.

The electrical igniter 30 utilized in the heater 10 of this invention is constructed of 20 gauge, i.e., 0.032 inch diameter, wire manufactured byKanthal Corporation under the tradename Kanthal A-l. This wire has a resistance factor of 0.8537 ohms/foot at room temperature. A temperature of about 2200 degrees F is the maximum to be allowed in order that destruction of the wire be prevented. The igniter 30 comprises two straight portions of wire connected by a coil of the wire. The total length of the wire is designed to produce a resistance of about one-half ohm.

In the operation of the heater 10, the voltage on the igniter 30 is desired to be maintained within a range of from 4 volts DC. to 5.5 volts DC. The minimum voltage is a requirement of the temperature necessary to ignite the fuel. The maximum voltage is directly related to the maximum temperature attainable by the wire. In this respect, the voltage delivered to the igniter 30 may be maintained at any desirable level by one of a number of suitable electrical circuit arrangements. One such arrangement, involves placing an energy dissipating resistor in series with the igniter 30 of a value sufficient to assure that the voltage on the igniter never exceeds some arbitrary voltage below 5.5 volts D.C. Since, as noted above, the heater 10 is capable of operating on a power supply of either 12 volts DC. or 24 volts D.C., the resistor as explained above or any such arrangement, must include suitable accommodations for such changes in the power supply.

Although the decrease in current and time consumptions required to achieve total combustion of the fuel with the present invention are minimal, the primary advantage appears in the increase effectiveness of ignition. For example, the gradual heating of the block and immediate flame occurrance assist in carrying ignition completely through to full combustion without the flame being extinguished by air pressure produced by the fan 50.

Another benefit is the ability of the present invention to utilize heavier fuels such as what is commonly known as 2 diesel fuel. In the past, the thickness of this fuel resulted in much carbon build-up on the ceramic block 26. Although the fuel usually did ignite eventually, considerable difficulties were encountered with respect to bad ignition and rich fuel to air mixtures.

Modifications, changes and improvements to the preferred forms of the invention herein disclosed, described and illustrated may occur to those skilled in the art who come to understand the principles and precepts thereof. Accordingly, the scope of the patent to be issued hereon should not be limited to the particular embodiments of the invention set forth herein, but rather should be limited only by the advance by which the invention has promoted the art.

What is claimed is:

1. In a liquid fuel heater including a granular refactory block, two ports extending into the refactory block, a fuel supply means delivering fuel to said refactory block through a first of said ports, and means conveying air under pressure to penetrate said refactory block and vaporize the fuel delivered to the refactory block, an improvement in said liquid fuel heater comprising a cavity disposed entirely within the said refactory block, said two relatively adjacent ports terminating in said cavity, asbestos wick material positioned within said cavity, and igniter means supported adjacent to said asbestos wick material within a second of said ports.

2. The liquid fuel heater according to claim 1 in which the refactory block includes intersticial pores therein and the said cavity is characterized by dimensions substantially greater than the intersticial pores of said refactory block. 1

3. In a liquid fuel heater including a granular refactory block, a fuel supply means, air conveying means and an electrical resistance igniter, an improvement in the refactory block comprising said refactory block having a plurality of intersticial pores, a cavity disposed within said refactory block of a substantial size relative to one of said intersticial pores, a first port extending from the surface of said refactory block to said cavity receiving liquid fuel delivered by said fuel supply means, a second port extending from the surface of said refactory block into said cavity receiving said electrical resistance igniter and an asbestos wick positioned within said cavity absorbing liquid fuel delivered to said refactory block by said fuel supply means.

4. The liquid fuel heater according to claim 3 in which the electrical resistance igniter is positioned adjacent to said asbestos wick and ignites the fuel absorbed by said asbestos wick upon the energization of said electrical resistance igniter.

5. A method of igniting liquid fuel in a heater having a granular porous refactory block, fuel supply means, air pressure conveying means, and an electrical resistance igniter, comprising providing a cavity within the said refactory block, inserting an asbestos wick material into said cavity in the refactory block, connecting the fuel supply means to the refactory block through a first port extending from the surface of the refactory block to the said cavity, directing the delivery of liquid fuel to the refactory block to absorb the fuel into the said asbestos wick material and the porous refactory block, positioning the electrical resistance igniter immediately adjacent the asbestos wick material through a second port extending from the surface of the refactory block to the said cavity, energizing the electrical resistance igniter to ignite the liquid fuel absorbed by the asbestos wick material, and heating the refactory block by the initial ignition of fuel to assist in further vaporization and combustion of the liquid fuel.

6. A liquid fuel heater comprising a granular porous refactory block having intersticial cavities present therein, two relatively adjacent ports extending from the surface of the refactory block and terminating within the refactory block, a fuel supply means delivering liquid fuel to the intersticial cavities of said refactory block through a first one of said ports, means conveying air under pressure to penetrate said refactory block resulting in vaporization of said fuel delivered thereto, a cavity ofa substantial size relative to said intersticial cavities disposed within said refactory block, said ports terminating within said cavity, an asbestos wick positioned within said cavity, said asbestos wick absorbing a quantity of said fuel delivered to said refactory block, an electrical resistance igniter positioned within a second of said ports adjacent to said asbestos wick, and said electrical resistance igniter causing combustion of the fuel absorbed by said asbestos wick to thereby heat the said refactory block and assist in total combustion of the fuel delivered to said refactory block.

7. The liquid fuel heater according to claim 6 in which the electrical resistance igniter comprises a plurality of coils of electrically conducting, high resistance WII'e.

8. The liquid fuel heater according to claim 7 in which the electrical resistance igniter is positioned that the said plurality of coils extend only partially into the second of said ports whereby the fuel absorbed by said asbestos wick is ignited and sustained to heat the entire 

1. In a liquid fuel heater including a granular refactory block, two ports extending into the refactory block, a fuel supply means delivering fuel to said refactory block through a first of said ports, and means conveying air under pressure to penetrate said refactory block and vaporize the fuel delivered to the refactory block, an improvement in said liquid fuel heater comprising a cavity disposed entirely within the said refactory block, said two relatively adjacent ports terminating in said cavity, asbestos wick material positioned within said cavity, and igniter means supported adjacent to said asbestos wick material within a second of said ports.
 2. The liquid fuel heater according to claim 1 in which the refactory block includes intersticial pores therein and the said cavity is characterized by dimensions substantially greater than the intersticial pores of said refactory block.
 3. In a liquid fuel heater including a granular refactory block, a fuel supply means, air conveying means and an electrical resistance igniter, an improvement in the refactory block comprising said refactory block having a plurality of intersticial pores, a cavity disposed within said refactory block of a substantial size relative to one of said intersticial pores, a first port extending from the surface of said refactory block to said cavity receiving liquid fuel delivered by said fuel supply means, a second port extending from the surface of said refactory block into said cavity receiving said electrical resistance igniter and an asbestos wick positioned within said cavity absorbing liquid fuel delivered to said refactory block by said fuel supply means.
 4. The liquid fuel heater according to claim 3 in which the electrical resistance igniter is positioned adjacent to said asbestos wick and ignites the fuel absorbed by said asbestos wick upon the energization of said electrical resistance igniter.
 5. A method of igniting liquid fuel in a heater having a granular porous refactory block, fuel supply means, air pressure conveying means, and an electrical resistance igniter, comprising providing a cavity within the said refactory block, inserting an asbestos wick material into said cavity in the refactory block, connecting the fuel supply means to the refactory block through a first port extending from the surface of the refactory block to the said cavity, directing the delivery of liquid fuel to the refactory block to absorb the fuel into the said asbestos wick material and the porous refactory block, positioning the electrical resistance igniter immediately adjacent the asbestos wick material through a second port extending from the surface of the refactory block to the said cavity, energizing the electrical resistance igniter to ignite the liquid fuel absorbed by the asbestos wick material, and heating the refactory block by the initial ignition of fuel to assist in further vaporization and combustion of the liquid fuel.
 6. A liquid fuel heater comprising a granular porous refactory block having intersticial cavities present therein, two relatively adjacent ports extending from the surface of the refactory block and terminating within the refactory block, a fuel supply means delivering liquid fuel to the intersticial cavities of said refactory block through a first one of said ports, means conveying air under pressure to penetrate said refactory block resulting in vaporization of said fuel delivered thereto, a cavity of a substantial size relative to said intersticial cavities disposed within said refactory block, Said ports terminating within said cavity, an asbestos wick positioned within said cavity, said asbestos wick absorbing a quantity of said fuel delivered to said refactory block, an electrical resistance igniter positioned within a second of said ports adjacent to said asbestos wick, and said electrical resistance igniter causing combustion of the fuel absorbed by said asbestos wick to thereby heat the said refactory block and assist in total combustion of the fuel delivered to said refactory block.
 7. The liquid fuel heater according to claim 6 in which the electrical resistance igniter comprises a plurality of coils of electrically conducting, high resistance wire.
 8. The liquid fuel heater according to claim 7 in which the electrical resistance igniter is positioned that the said plurality of coils extend only partially into the second of said ports whereby the fuel absorbed by said asbestos wick is ignited and sustained to heat the entire refactory block. 